Deactivation of one or more cylinders of an engine may reduce emissions and improve fuel economy. During cylinder deactivation, the air charge in operating cylinders increases resulting in higher thermal efficiency and lower pumping losses, thereby decreasing fuel consumption. Further, the use of exhaust-gas recirculation (EGR) may provide additional fuel economy by introducing exhaust gas products back into the cylinders of the engine. Increasing swirl in the cylinder during low load and EGR conditions, for example when the deactivatable cylinders are deactivated, may promote effective combustion of fuel.
For example, Albertson in U.S. Pat. No. 6,557,518 discloses a system to deactivate a cylinder by disabling an intake and exhaust valve of the deactivatable cylinder by disabling hydraulic lash adjusters. Thus, the intake and exhaust valves are simultaneously closed.
However, the inventors herein have recognized a potential issue with Albertson et al. The disclosed system does not allow for increased swirl in cylinders as the intake and exhaust valve are both disabled when a cylinder is deactivated.
One potential approach to at least partially address some of the above issues includes systems and methods of providing an improved valve deactivation system for an engine wherein cylinder deactivation and/or high swirl may both be delivered. The engine valve deactivation system for an engine comprising two or more cylinders wherein each cylinder has two exhaust valves and two inlet valves. The at least one deactivatable cylinder has one inlet valve selectively deactivated by means of a first supply of pressurized fluid and both the exhaust valves and the other one of the inlet valves are selectively deactivated by means of a second supply of pressurized fluid.
For example, the first supply of pressurized fluid may be used to deactivate the one inlet valve during engine operating conditions where an increase in swirl in the cylinder is desired, such as at light load and EGR being supplied. The second supply of pressurized fluid and the first supply of pressurized fluid may be used to deactivate a cylinder under low load. Thus, a system is provided which allows for cylinder deactivation or high swirl to be delivered.
Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.